Papermaking machine pickup device including an inflatable member pressing an apron uniformly against the web

ABSTRACT

A device for removing or couching a fibrous web from either the forming wire of a Fourdrinier machine or the surface of a forming roll (or cylinder) in the case of a cylinder type machine which includes a smooth apron which contacts the web and an inflatable, elastomeric, hollow member which presses the apron against the web in a uniform fashion. The hollow member can be filled to an adjustable level with liquids or gases.

Apnl 24. 1973 s. s. STEVENS 3,729,376

PAPEHMAKING MACHINE PICKUP DEVICE INCLUDING AN INFLATABLE MEMBER PRESSINGAN APRON UNIFORMLY AGAINST THE WEB Filed Oct. 23, 1970 'fi F I 3 II. II -28 ll 2 O TT\\:\\ u 1 15 1 12 V V u INVENTOR SAMUEL S. STEVENS ATTORNEY United States Patent O 3,729 376 PAPERMAKING MACHINE PICKUP DEVICE IN- CLUDING AN INFLATABLE MEMBER PRESS- ING AN APRON UNIFORMLY AGAINST THE WEB Samuel S. Stevens, Box 218, Erving, Mass. 01344 Filed Oct. 23, 1970, Ser. No. 83,347 Int. Cl. DZlf 2/00 US. Cl. 162-306 7 Claims ABSTRACT OF THE DISCLOSURE A device for removing or couching a fibrous web from either the forming wire of a Fourdrinier machine or the surface of a forming roll (or cylinder) in the case of a cylinder type machine which includes a -smooth apron which contacts the web and an inflatable, elastomeric, hollow member which presses the apron against the web in a uniform fashion. The hollow member can be filled to an adjustable level with liquids or gases.

BACKGROUND OF THE INVENTION One of the obstacles to good papermaking resides in the non-uniformity of the couch pressure due to unevenness in the couch face for instance, which is of a rubber-like material. The cylinder forming roll also has a non-uniform surface, and in some cases in a Fourdrinier, the wire has uneven tension in spots. This causes an uneven web, i.e., the web thickness is not uniform, and therefore the paper produced is necessarily of uneven caliper. This results in a poor web pickup by the felt.

It is the object of this invention to provide a uniform self-equalizing surface across the couch, to obviate wear on the couch roll, and in fact to do away with the couch as it is known in the prior art, particularly the upper roll in a Fourdrinier, and the couch roll in a cylinder forming machine, while at the same time providing absolute uniform pressure on the wire completely across the same, resulting in greatly improved caliper and web pickup.

SUMMARY OF THE INVENTION In the case of a cylinder forming machine the couch roll commonly used with the forming roll is obviated. The forming roll rotates, forming the web as is well known, and the felt takes the sheet from the forming roll under influence of a member which is in the nature of a hollow pressurized inflatable distortable shoe, with means for varying the pressure therein, there being a smooth, slick apron in fixed position between the forming roll and the inflatable member, said apron being formed of a smooth plastic or impregated textile, etc.

This inflatable member provides a self-equalizing surface having an absolutely uniform couch pressure across the machine and compensates for non-uniformity of the cylinder forming roll, bottom couch roll, or for uneven tension in the Fourdrinier wire. Because of the gas or fluid in the inflatable member, it presses the couch face equally at all points and any inequalities (e.g. in the surface of the forming roll, etc.) are instantly equalized, completely across the face, providing completely uniform pickup pressure at all points thereon thereby minimizing pickup problems.

In the case of a Fourdrinier, a bottom couch roll is used but the top couch roll was substituted for it the inflatable hollow member and apron above described. There is however a different form of the invention possible with a Fourdrinier wire. and that is that the same or similar inflatable hollow member can be applied directly to the wire rather than to the bottom couch roll slightly in advance of the latter, so that there is no pressure on the couch roll except that due to the wire itself which passes around the bottom couch roll to return to the slice, and in all cases the inflatable member assures absolutely uniform pressure, and hence produces a more uniform web across the entire width of the wire or couch roll and a greatly improved pickup of the sheet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic showing of the invention as applied to a forming cylinder;

FIG. 2 is a similar view showing the invention applied to a Fourdrinier; and

FIG. 3 is a view showing the invention applied to the Fourdrinier in a different manner.

PREFERRED EMBODIMENT OF THE INVENTION In FIG. 1, the reference numeral 10 indicates the forming roll or cylinder which is rotating in a counterclockwise direction. The felt is indicated at 12 and this is traveling as shown by the arrows thereon. As is well known, the stock is applied to the forming roll at the right-hand side thereof, the water is extracted to the degree desired, by suction, and the web is then taken off at the under side of the felt in the direction of travel thereof.

Instead of using a couch roll, there is provided an inflatable member comprising an elastomeric hollow shoe or container generally indicated at 14 mounted on a block or the like 16 and having pipes at 18 by which it may be filled or emptied with fluids, i.e., gas or liquids, to an adjustable degree. The support 16 is mounted on a lever 20 pivoted at 22 from a support not shown. The free end of the lever at 24 is adjustably positioned by a piston rod 26 energized by a double action cylinder 28 mounted in any way desired as on a plate 30.

The bottom portion of the hollow member 14 may be e.g. formed on an arc of a circle as is indicated at 32 and it presses with the force necessary against the felt and in turn against the forming roll. Sometimes the member 14 should be of a different hardness, so pressure inside the same can be either added to (or lessened) as for instance by means of a valve in the line 18, and the pressure with which it is applied to the felt and the forming roll is determined by the amount of pressure derived from cylinder 28. An apron which is indicated at 34 is for instance rolled in a coil 36 and taken up by a conventional takeup means e.g. roll 38 operated by a crank handle 38a, e.g. This apron is in fixed position between the pressure member 14 and the felt and the reason for making it in the form of a strip which can be longitudinally adjusted is to provide for wear.

The apron is made of a suitable plastic such as for instance Teflon having a very low friction. Other plastics can also be used and also impregnated textiles, etc., and in any even the apron has very low abrasion and friction characteristics.

Referring now to FIG. 2, there is shown a Fourdrinier wire at 40 traveling in the direction shown about the bottom couch roll 42 which is being rotated counterclockwise. The felt is shown at 12' and this felt is substantially the same as before as is also the rest of the apparatus including the apron 34. The apron mounting and takeup roll, the supply for the elastometric hollow member or shoe 14, supporting lever 20', double action cylinder 28', etc., are all the same as before. The operation is substantially the same as above described, the only dilference being that the invention is applied to the bottom couch roll of the Fourdrinier wire, obviating the upper couch roll.

In FIG. 3 the bottom couch roll is shown at 42", the Fourdrinier wire at 40", and the felt at 12", the apron at 3 34", the distortable member at 14", the support at 20", and the double action cylinder at 28".

However in this case the member 14'' does not act against the bottom couch roll at all but against the Fourdrinier wire 40" in advance of the bottom couch roll. However the action is the same as above described, the felt 12 taking off the web from the Fourdrinier wire, as in FIG. 2.

The pressure across the machine is equalized in all cases by the use of the inflatable shoe. In the prior art, projections or hollows in the forming roll screen or in the Fourdrinier wire causes bumps or lumps, but with the inflatable member 14 this is obviated as the flexible shoe surface will conform in all instances to the forming roll or Fourdrinier wire, completely across the machine, forming a more uniform web with improved caliper and sheet pickup. Present couch rolls e.g. made of rubber-like materials cannot be equalized as to pressure across the face of the roll and cannot assure uniform pickup pressure at all points.

I claim:

1. A papermaking machine including a web forming apparatus, a felt adapted to take the Web from the Web forming apparatus, means forming a self-equalizing surface across the felt and the web forming apparatus at the area of pickup of the web from the web forming apparatus, a stationary antifriction element between the means forming the self-equalizing element and the felt,

the means forming the self-equalizing surface applying uniform pressure comprising an elastomeric hollow member, means for inflating the same with a fluid medium, and means applying the hollow member to the anti-friction element and thereby to the felt at said area.

2. The papermaking machine of claim 1 wherein the anti-friction element is an apron.

3. The papermaking apparatus of claim 2 wherein said anti-friction apron is stationary, and including means for adjusting the apron in a direction parallel to the felt so that the inflatable member bears on a different portion of the apron.

4. The papermaking apparatus of claim 1 including means to vary the pressure of the inflatable member.

5. The papermaking apparatus of claim 1 wherein said web forming apparatus is the forming roll of a cylinder type of papermaking machine.

6. The papermaking machine of claim 1 wherein the web forming apparatus is a Fourdrinier machine, having a bottom couch roll and the inflatable member bears on the bottom couch roll.

7. The papermaking machine of claim 1 wherein the web forming apparatus is a Fourdrinier machine, and the inflatable member bears on the felt, the web, and Fourdrinier wire.

References Cited UNITED STATES PATENTS 3,293,121 12/1966 Martin 162-358 3,528,881 9/1970 Stucbe 1'62306 3,537,955 11/1970 Huerta et al. 162306 2,748,671 6/1956 Heys 162306 3,515,637 6/1970 Reynolds et a1. 162306 X S. LEON BASHORE, Primary Examiner R. H. TUSHIN, Assistant Examiner US. Cl. X.R. 

